John w



(No Model.)

' J. W. POST. i TENSION DEVICE FOR SEWING MACHINES'.

No. 373,852. y

,Z terne Patented Nov. 29,7188?.

UNITED STATES PATENT OFFICE.

JOHN W. POST, OF NEW YORK, N. Y., ASSIGNOR TO THE CHILDS SEWING MACHINE COMPANY.

TENSION DEVICE FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 373,852, dated November 29, 1887.

` Application filed July 23, 1886. Serial No. 208,857. (No model.)

To all whom, it may concern.- A

Be it known that I, JOHN W. Posr-` a citizen of the United States, residing at New York city, in the county of New York and State of New York, have invented cert-ain new and useful Improvements in Tension Devices for Sewing- Machines;'aud I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

Referring to the drawings, Figure l is a front elevation of the head of the overhanging arm of a sewing-machine provided with myimproved tension devices. Fig. 2 isa vertical transverse section thereof. Fig. 3 is a horizontal transverse section taken on line :v x of Fig. l; and Figs. 4 and 5 are isometric views of the tension-plates for the upper tension, drawn to an enlarged scale.

This invention relates to improvements in sewing-machines, and more especially to those devices employed in the machines known as threadtensions;7 and it consists in the construction of the devices, substantially as hereinafter fully described,-and as set forth in the claims. Y

In the drawings, H indicates the head on the outer end of the overhanging arm of a sewing-machine,inwhichareformed,asusual,bear ings for both he presser-bar B and the needle- `bar N.

My improved tension consists of two tension-plates, P and P, both having a central perforation, p, the tension-plate P being besides provided on diagonally-opposite corners with a depending lug, p and p", respectively, so that when said plate P is seated on plate P and on the head H of the overhangin'g arm of the machine the tension-plates will be held against accidental displacement on each other and on the head of the machine. The lugs p p2v also serve to guide the plates P P in their vertical movements in adjusting the tension, which is effected by the following instrumentalities:

In the head H is formed a socket, h, the

lower portion, h', of which is of reduced diameter and screw-threaded interior] y. In said socket is arranged a rod, R, the lower portion of which is also reduced in diameter, screwthreaded, and screwed into the portion h of socket h. The rod carries at its outer end a milled or other head for rotating the same,and on said rod is mounted a coiled spring, S, and the tension-plates P and P in the order named. The lower end of the spring abuts against the shoulder h2, formed by the contracted portion of slot h, while its upper end abuts on the under side of the lower tension-plate, P', the upper tension-plate,P,bearing against the under face of the milled heads of rod R, as shown. The needle-thread as it comes from the spool passes between the two plates P and P', and thence in any usual manner down to the nee- `dle,'preferably toa thread-check or lower tension device, presently to be described. The lugs 10 and p2 on the diagonally-opposite corners of the upper tension-plate, P, also serve to hold the needle-thread between it and plate P and prevent it from being jerked out during the operation of the machine. It is obvious that by screwing the rod in or out of the threaded portion h of socket h the tension of the spring S will be increased or decreased to correspondingly increase or decrease the pressure of. plate P on plate P, and consequently on the needle-thread lying between them. The spring S also holds the plate P with a yielding pressure against the plate P, so that the thread will not break on being drawn through.

Near the lower end of the head of the overhanging arm of the machine is arranged a thread-check, which is constructed as follows, referring more particularly to Fig. 3:

In the lower end ofthe head H is an opening, in which is tted a hollow pin, A, that has a notch or slit, a, near its head a', said pin being fitted in the opening in the head H, so that the slit a will lie flush with or slightly beyond the front face of said head.

In the pin A is fitted a piston or plunger, B', the rod of which is encircled by a coiled spring, b. The plunger is made' shorter than the hol- Ilow or tubular portion of the pin A, with which tubular portion the slit or notch a communicates, and the open end of the pin is screwthreaded interiorly to receive the adjusting-screw C. One end of the spring b bears upon the inner face of the screw C and the other upon the rear face of the piston-head 5 b2, thus forcing the latter against the head of the pin A,and when the needlethread is passed between said head and plunger the check nut or screw acts as a checking device for said thread, as will be readily understood.

Having now particularly described my said invention, what I claim, and desire to secure by Letters Patent, is-

l. The herein-described tension device for sewing-machines,consisting of the two rectanguiar plates having the perforations, the adjustable screw passing through them, and the spring for pressing them together, one of said plates having projections or lugs engagingthe other and preventing independent rotary inotion of the plates on the screw, substantially as described.

2. The hereindescrbed tension device for sewing-machines, consisting of the two plates having the pcrforations, the adjustable screw passing through them, the spring for pressing them together, one of said plates having the projections engaging the other plate and also engagingaportion of the frame for preventing the rotary motion of the plates as regards each 3o other and the frame, substantially as described.

3. The combination,with the machine-head, ofthe two rectangular plates between which thethread passes, the upper one having thelugs p p2, passing on opposite sides of the lower plate and engaging the sides of the head, and the spring and adjusting-screw, substantially as described.

4. The combination,with the needle-bar and needle, ofa th read-check consisting of the hollow pin having the transverse slot,the plunger located within said pin, and the spring for pressing it toward the slot, substantially as described.

5. The combination,with the needle-bar and needle, ofa thread-check consisting of the hollow pin having the transverse slot, one end of the pin forming a head adjacent to the slot, the plunger located within the pin, the spring for pressing said plunger toward the head, and thescrew foradjusting thetension ofthespring, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN WV. POST.

Witnesses:

FRANK M. GREEN, HENRY ORTH. 

